I removed the mechanical plastic fan and installed a Hayden 10" fan in the puller position along with adjustable temp. control.
Generally, many owners reported insufficient space between rad and water pump pulley with CB models. Mounting the fan as far to the drivers side as possible and spacing the alloy rad (non-stock) 3/8" forward worked out well. This is where hot water enters the rad. Also, I had the water pump double pulley machined to retain only the single belt arrangement for extra clearance and a bit of weight saving. The rad support braces needed small adjustments-slotted holes.
I did use the plastic tie mount system provided with the fan - might consider making up metal brackets instead at a later date.
The engine reaches operating temp. more quickly now, the coolant thermostat is a 180 F.and in 25 C. ambient the electric fan only comes on briefly during stop and go traffic. Open road running without fan noise is great.
Late B's all had electric fan's, I'm not too far off original. Perhaps a minor improvement in reducing parasitic power losses is welcome.